Presentation
Ankle sprain 10 days ago; now ankle pain and swelling around the lateral malleolus.
Patient Data
Age: 50 years
Gender: Female
From the case:
Ankle teardrop sign
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Info

Ill-defined oval opacity projected over the anterior recess (so called "ankle teardrop sign") of the left ankle joint, in keeping with a joint effusion.
No evidence of fracture or dislocation.
Case Discussion
The teardrop-shaped opacity represents fluid in the inferior space of the anterior compartment of the ankle joint.
It has been postulated that at least 5 mL of effusion is needed in order to depict it using a lateral x-ray projection in the neutral position.